Vacuum cleaner



H. E. VMETZ VACUUM CLEANER Filed March 31, 1947 W2 MU M Y p M H MM @M @N Nov. 21, 1950 Patented Nov. 21, 1950 VACUUM CLEANER Harry E. Metz, New Britain, Conn., assignor to Landers, Frary & Clark, New Britain, Conn., a corporation of Connecticut Application March 31, 1947, Serial No. 738,247

3 Claims.

to tank type vacuum cleaners which are provided with an electric motor for driving a fan assembly with the fan assembly and the motor positioned centrally of the tank with the motor in the path of the air stream. In constructions of this kind,

the cooling of the motor is almost entirely dependent on the absorption of heat by the air being driven through the tank while the heat loss through conduction is substantially negligible. Despite the great volume of air which normally is passed through the tank, it has been found that the motor tends to overheat and the cooling effeet is uneven so as to provide many points of localized overheating.

It is an object of the present invention to provide a baffle construction for such tank type vacuum cleaners which will cause a reduction in the motor operating temperature and which will avoid localized or general overheating, thereby providing a longer useful life for the motor.

A further object of the invention is to accomplish the foregoing object without the use of complicated mechanisms or baflle arrangements which might interfere with the normal efiicient action of the cleaner and without increasing the expense and complicating the assembly of the cleaner to an extent which would depreciate the value of the increased cooling.

A more general object of the invention is to provide means for making more efficient use of the air stream as a cooling medium for the motor and for causing more uniform cooling of the various motor parts.

Other objects will be in part obvious and in part pointed out more in detail hereinafter.

The invention accordingly consists in the features of construction, combination of elements and arrangement of parts which will be exemplified in the construction hereafter set forth and the scope of the application of which will be indicated in the appended claims.

The single figure of the drawing is a, side view, partially in cross section, of a tank type vacuum cleaner embodying the deflector shield arrangement of the present invention.

Referring to the drawing, the body of the vacuum cleaner is shown as a tank or cylindrical housing II] in which is mounted, slightly to the rear, an electric motor generally denoted by the reference numeral II having a shaft I2 on the front of which is mounted a fan assembly I3.

The motor II is a conventional electric motor having a frame I4 comprising front and rear cupshaped portions I5 and I6, respectively, and with the field windings or coils I! mounted therebetween. The armature I8 and commutator I9 are mounted on the shaft I2 in the usual manner.

The front of the shaft I2 is mounted in a hearing 20 which is carried by the front cup-shaped portion I5 of the frame I I which, in turn, is secured to a fanassembly housing 2| which is resiliently mounted within the tank or cylindrical housing In by means of a rubber ring 22. The rear end of the shaft I2 is supported in a bearing 23 which is carried on the rear cup-shaped portion I6 of the frame It by brackets 24. The rear end of the motor adjacent the bearing 23 is resiliently supported in a rubber bushing 25 which is received by the interior housing 26 which is secured to the tank or cylindrical housing It].

In the operation of the device as so far described, air is drawn in from the nose of the tank or cylindrical housing III (at the left side of the vacuum cleaner as viewed in the drawing) where it passes through a dust collecting bag 21 and thence through a filter 28 which is positioned'in a filter housing 29 attached to the fan assembly housing 2|. The air then passes from the fan assembly through orifices 33 in the front cupshaped portion I5 so as to flow through and around the motor I I and is released through the openings 39 in the interior housing 26 and from thence through a filter 3| and finally escapes through the coupling or socket 32 in the rear end of the cleaner.

In accordance with the present invention, it has been found that by providing a baffie 35 extendin around the motor I I between the periphcries of the front and rear. cup-shaped portions I5 and It, there is an unexpected and extraordinary increase in the cooling action of the air stream which materially decreases localized heating, all of which is accomplished without in any way detracting from the efiiciency of the cleaner. With the construction as heretofore utilized, i. e., without the baffle 35, the air received within the front cup-shaped portion l5 partially flows through the interior of the motor and. around the exterior of the field coils and commutator passing through orifices 34 in the rear cup-shaped portion I6, but a great proportion of the air escapes outwardly between cup-shaped portions l5 and It in turbulent flow into the area defined by the interior housing 26. With the baffle 35 in place, there is apparently a greatly increased flow through the interior of the motor and a resulting more efficient cooling of the rear portions thereof. In general, the air flow with the baflle 35 in place is believed to be as indicated by the arrows of the drawing, i. e., the air is directed inwardly through orifices 33 in the front cup-shaped por tion l5 taking'a divided path "outside and inside the field windings I l to the rear cup-shaped portion I6 from whence it escape through orifices 34. While it is not intended to limit the invention to any theory of operation, it is believed that the decrease in cross sectional area provided by the inclination of the baflle toward the rear cup-shaped portion l6 causes an increase in speed of the air at the rear end of the motor H forming a low pressure area which greatly increases the flow of air through the interior of the motor.

As will be apparent, it would be impracticable to funnel all of "the air through the interior "of the motor 'l'l because of the small amount of space available which would build upc'onsiderable pressure in the tank and materially decrease the efficiency of the cleaner. Accordingly, the provision of a controlled air flow around the exterior 'of the rnotor which increases the "flow of air through the interior of the motor provides many desirable advantages. 4

The unex ected and extraordinary results obtained by the use of the baffle 35 as explained above has been adequately demonstrated by actual tests under standard conditions. As aspec'ific example of such tests, a standard vacuum cleaner without the baffle 35 was operated at half load at ordinary room temperatures and then the operation 'was repeated with the same vacuum cleaner under same load conditions and exterior temperature conditions. During each run the temperature of various portions of the motor were fmeasured b'y thermocouple arrangements. The following is a selection of representative readings- Referrinlgto the above test figures, it will be seen that Without the motor baffle there is a temperature range or differential present of 65 indicating localized overheating at the rear end of the motor whereas with the motor bafile in place the temperature spread is less than half, i. e., 28".

The greatest reduction in temperature is found at the rearmost location of the temperature testing equipment, thus demonstrating the effectiveness of the present construction for alleviating the overheating of the rear end of the motor.

"It'thus will be seen that there has been provided, in accordance with the invention, a'simple and effective arrangement for controlling the air now through a tank ty'pe vacuum cleaner so that more efficient and uniform cooling of the motor results Without at the same time providing a complicated path for the air streamyvhich might affect the efiiciency of the vacuum cleaner. The construction of the present invention is simple and economical to manufacture and assemble and the results "obtained are clearly advantageous 4 and constitute a distinct improvement over prior' art constructions.

As many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description for shown in the accompanying drawingssh-all'b'e interpretedas illustrative and not in a limiting sense.

-It is also to be understood that the language used in the following claims is intended to cover all of the generic and specific features of the invention herein described and all statements of the scope of the invention which, a a matter of language, mightbe said to fall therebetween.

I claim as my invention:

1. In a vacuum cleaner of the tank type, a cylindrical outer housing, a fan assembly for causing a flow of air through said housing, an

electric 'inctor for driving the fan assembly-having a'frame comprising perforate front and"rear forwardly facing cup portio'ns, said front oup'portio'n having perforations directed inwardly and outwardly of the motor and said outer housing being spaced from the peripheries of said cup portions, a housing for the fan assembly 'arranged to direct the flow of air to the front cup portion of the motor frame, and a bafile extendingarour'id the frame between the peripheries "of said mp portions of the motor frame forming an enclosed airpassageway betwen said cup portio-ns, whereby the motor operatin temperature is reduced.

2. 'In a vacuum cleaner of the tank type, a cylindrical outer housing, a fan assembly for causing "a flow of air through said housing, an eleoti'ic motor fbr driving the can assembly 'Of the type having aframe comprising a perforate for- "wardly facing front cup portion and'a perforate forwardly facing rear cup portion of smaller diameter than the front cup portion, said perforations in the front cup portion being directed inwardly and outwardly of the 'motor and said outer housing being spaced from the peripheries of said cup portions, a housing for the fan assembly arranged to "direct the flow of air to the front 'cup portion of the motor frame, and a frusto conica'l bafile extendin between the pe ripheries of said cup portions of the motor frame forn'iin'g an enclosedair passageway of decreasing cross'sectiohal area "from front to rear cup 1561- tions whereby the motor operating temperature is reduced.

3. In a, vacuum cleaner of the tank ty'pt, a cylindrical outer housing, a fan assembly for causing a flow of air through said housing, an electric motor for driving said fan-assembly of the type having a frame comprising a forwardly facing front cup portion having orifices for directing air inwardly and outwardly of the frafne and aforwar'dly facing rear cup portion of smaller diameter than said front portion having orifices for releasing "air adjacent the commutator of the motor and having a field winding disposed between said cup portions, said outer housing being spaced from the peripheriesof said cup portions, a housing for the fan assembly arranged to'dire'ct the flow of air to the front cup portion ofthe motor frame, and a fnusto-conicalbaflleextending between the "peripheries of said 'cu'p portions of the motor frame and spaced from said field wading forming an enclosed air passageway for 'd ecting the air 'fiov'v received outwardly of the frame 'thrb'ugh said orifices tr the front cup portion to the rear cup shaped. portion at-an accelerating rate of flow thereby increasing the flow of air through the interior of the frame and reducing the motor operating temperature at the commutator end thereof.

HARRY E. METZ.

REFERENCES CITED The following references are of record in the file of this patent:

Number 6 UNITED STATES PATENTS Name Date Bimm May 9, 1922 McClatchie July 16, 1929 Lofgren Apr. 25, 1939 Kroenlein Mar. 20, 1945 

